The present invention relates to a print control device for an electrophotographic printer which is a dumb print system.
In general, an electrophotographic printer comprises a data process controller for processing print data, an engine for performing a printing operation, and an engine controller for controlling the engine. In the case of the dumb print system, printing is performed while a data process controller receives the print data from a host system. Therefore, when the data process controller receives at least the initial line of print data, the engine controller is started, a paper is fed to the engine, and a print drum rotates at a predetermined speed. An electrostatic latent image is then formed on a surface of the print drum by exposure light emitted from a print head and developed by toner supplied from a developing unit, and the developed toner image is transferred onto the paper by a transfer unit and fixed by a fixing unit. In this case, by synchronizing the transmission speed of the print data from the host system and the rotating speed of the print drum, a good match can be obtained between the print data flow from the host system and the transport speed of the paper.
However, the following problem is encountered with the above-mentioned prior art. In cases where the data processing capability of the host system is inferior in comparison to the performance of the engine of the printer, print data transmission can not be synchronized to the rotating speed of the print drum. As a result, a case has occurred wherein after the printer has printed one line and before the print data of the next line are sent from the host system, the print drum transports the paper by more than the width of the one line. In such case, exposure by the print head can not keep pace with the paper transport (termed under-run) and empty spaces were produced between lines.